Creatine Augmentation in Veterans With Selective Serotonin Reuptake Inhibitor (SSRI)-Resistant Major Depression

• Change in Montgomery-Asberg Depression Rating Scale (MADRS) Score [ Time Frame: screening; baseline; weeks 1, 2, 4, 5, 8, and 10 ] [ Designated as safety issue: No ]
  The primary clinical outcome measure will be the change in MADRS; response will be defined as a 50% or greater decrease in MADRS score from baseline and a Clinical Global Impression Scale (CGI) improvement score of 1 or 2
  
  

• Changes in 3T 31Phosphorus Magnetic Resonance Spectroscopy metabolites [ Time Frame: Baseline and 8 weeks ] [ Designated as safety issue: No ]
  The primary neuroimaging outcome measures will be changes in 3T 31P-MRS metabolites (PCr and β-NTP) globally and in the anterior cingulate cortex
  
  

This is an open-label clinical trial of the investigational drug creatine for augmentation treatment of male veterans, ages 18-55, with Major Depressive Disorder (MDD) who have failed to respond to first-line SSRI treatment.

Despite the existence of currently available antidepressant treatments, major depressive disorder (MDD) remains a leading cause of disability and suffering in this country (Kessler et al 2003). Furthermore, patients with MDD are at significant risk for suicide attempts and completed suicide (Claassen et al 2007). MDD is also common among the veteran population. During fiscal year 2007, the Salt Lake VA saw 1,936 unique patients with a documented diagnosis of MDD.

Although various antidepressant treatments are currently available, a significant proportion of individuals with MDD either do not respond to, respond inadequately to, or cannot tolerate adequate doses of available antidepressant medications. Thus, the need remains to develop novel antidepressant treatments which may be more effective and/or better tolerated in treatment-resistant depression. While progress has been made in recent years in understanding aspects of the neurobiology of this condition, a more comprehensive understanding of the neurobiology of depression is still lacking and is a major obstacle to the development of more effective therapies for this disorder.

Widely used by high school and college athletes in the U.S., creatine is an over-the-counter nutritional supplement with annual sales of more than $200 million. Studies in animals show that creatine improves the performance of female rats in the Porsolt Forced Swim test, which is used to predict the efficacy antidepressant compounds. Human neuroimaging studies indicate that patients with MDD have abnormal levels of high-energy phosphate metabolites in brain, primarily adenosine triphosphate (ATP) and phosphocreatine. Research has also shown that creatine supplementation induces changes in these high-energy phosphate metabolites that are associated with a positive response to antidepressants.

Based on previous preclinical and clinical studies, we propose that the nutritional supplement creatine may be a helpful adjunctive treatment for treatment-resistant depression.

For the proposed study, twenty male veterans between the ages of 18-55 with MDD will be recruited for participation in an open-label trial of creatine. Participants with depression will have unremitted MDD despite treatment with an adequate trial of an approved SSRI. Depressed participants will be treated with oral creatine 5 gm daily for eight weeks and will continue to take their current SSRI prescription. In addition, twenty healthy control participants, also male veterans between the ages of 18-55, with no history of psychiatric or substance abuse disorder will be recruited. No treatment will be administered to control participants.

The primary outcome measure for antidepressant efficacy will be the change in Montgomery-Asberg Depression Rating Scale. For MRS, primary parameters of interest to be measured include concentrations of b-NTP (primarily reflecting ATP), phosphocreatine, pHi, creatine, and NAA. MDD participants will undergo brain scans at baseline and again after eight weeks, with 31-Phosphorus Magnetic Resonance Spectroscopy (31P-MRS). Healthy controls will undergo a single brain scan. The brain scans will be used to measure high-energy phosphate metabolites globally and in the Anterior Cingulate Cortex (ACC), a region of the brain that has been implicated in MDD. 31P-MRS is a non-invasive neuroimaging technique that does not expose participants to radiation. At the magnetic field strength utilized (3T), magnetic resonance imaging is FDA-approved and has no known adverse effects. The research team will use data from 31P-MRS scans to compare levels of high-energy phosphate metabolites in MDD participants vs. healthy controls. In addition, comparison of pre- and post-treatment metabolite levels will be conducted in the MDD participants.

The primary hypothesis is that oral creatine supplementation will have a beneficial effect as adjunctive therapy in adult male veterans with MDD who are non-responders to an adequate trial of standard SSRI antidepressant treatment. Secondary hypotheses include the following: MDD participants will demonstrate differences from healthy controls in bioenergetic parameters in anterior cingulate cortex and more globally in the brain, as measured by 1H-MRS and 31P-MRS; and that depressed participants who respond to oral creatine supplementation will show bioenergetic changes in the anterior cingulate cortex and globally in the direction of the healthy controls.